Genetic Variability in a Rice Breeding Population for Cold Tolerance In Southern Brazil

Abiotic stress such as low temperature can negatively affect crop production. Rio Grande do Sul (RS) state is the most important rice producer of Brazil with 63% of total production. In RS, irrigated rice is grown generally from October to April and in some producing regions, low temperatures occur during the reproductive stage of rice which can be extremely harmful to crop. The aim of this study was to identify genetic variability in a breeding population for cold tolerance during the reproductive stage in order to map genes conferring resistance/tolerance. The experiment was conducted during the 2011/2012 season, in Capão do Leão and Santa Vitória do Palmar cities, RS. The experimental design was an augmented design from Federer for F₅ families from population and controls Nipponbare (cold tolerant) and BRS-Atalanta (cold sensitive) were randomized every 25 families. Phenotypic characters like plant height, panicle size, degree of panicle exertion, sterility percentage and total of grains were collected. The population showed significant differences among many families for all observed traits. The Scott Knott test, UPGMA hierarchical clustering and Principal component analysis showed the formation of distinct groups of families considering all the traits and for traits related to the reproductive stage, percentage of sterility and degree of panicle exertion. The results show that the population presents variability for the characters allowing use of the population for further genetic studies.